CN117471608A - Filter based on multimode sub-wavelength grating - Google Patents
Filter based on multimode sub-wavelength grating Download PDFInfo
- Publication number
- CN117471608A CN117471608A CN202311405720.1A CN202311405720A CN117471608A CN 117471608 A CN117471608 A CN 117471608A CN 202311405720 A CN202311405720 A CN 202311405720A CN 117471608 A CN117471608 A CN 117471608A
- Authority
- CN
- China
- Prior art keywords
- sub
- wavelength grating
- mode
- waveguide
- grating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 11
- 230000033228 biological regulation Effects 0.000 claims abstract description 5
- 230000008859 change Effects 0.000 claims description 71
- 230000003287 optical effect Effects 0.000 claims description 16
- 230000008878 coupling Effects 0.000 claims description 14
- 238000010168 coupling process Methods 0.000 claims description 14
- 238000005859 coupling reaction Methods 0.000 claims description 14
- 238000009826 distribution Methods 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 238000012886 linear function Methods 0.000 claims description 3
- 230000003595 spectral effect Effects 0.000 abstract description 9
- 238000001228 spectrum Methods 0.000 abstract description 7
- 230000004044 response Effects 0.000 abstract description 4
- 239000006185 dispersion Substances 0.000 abstract description 2
- 238000000034 method Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 238000005253 cladding Methods 0.000 description 3
- 238000004891 communication Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000005693 optoelectronics Effects 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 241001270131 Agaricus moelleri Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 239000012792 core layer Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002070 nanowire Substances 0.000 description 1
- 230000008844 regulatory mechanism Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 210000003781 tooth socket Anatomy 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12083—Constructional arrangements
- G02B2006/12109—Filter
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12133—Functions
- G02B2006/12164—Multiplexing; Demultiplexing
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention discloses a filter based on multimode sub-wavelength grating. The filter includes a mode demultiplexer for multiplexing and demultiplexing of the fundamental and higher modes, including a sub-wavelength grating for mode field weak-confinement modulation of the fundamental and higher modes, including a pass-through waveguide for the output of the fundamental mode. According to the invention, by introducing the structure of the sub-wavelength grating and the regulation and control on the weak constraint of the mode field, and by virtue of the excellent gentle dispersion regulation and control characteristic, the grating local refractive index which is consistent with the apodization of the grating is still maintained, so that the filter with high side mode rejection ratio and no free spectrum range limitation is obtained, the flattened and low-loss spectral response can be realized, the next-generation high-capacity and high-speed wavelength division multiplexing transmission requirement is met, the bandwidth design is more flexible, and the filter has the advantages of simple structure, simple process, excellent performance and the like.
Description
Technical Field
The invention relates to a filter, relates to the field of integrated optoelectronic devices, and in particular relates to a filter based on multimode sub-wavelength gratings.
Background
Silicon-based optoelectronic technology is becoming more and more interesting in academia and industry because of its advantages of large bandwidth, high integration density, low energy consumption, low cost, and compatibility with CMOS (Complementary Metal Oxide Semiconductor ), and is considered one of the most promising and potentially cost-effective technologies, and can be used as a core support technology for next-generation optical communication, optical interconnection, and optical sensing systems. Among the numerous device structures of silicon-based optoelectronic systems, bragg gratings are widely used in wavelength division multiplexing, spectral analysis, nonlinearity, etc. scenarios due to their large free spectral range (Free Spectral Range, FSR), flattened spectrum and high flexibility. The multimode waveguide grating provides a waveguide structure with great development potential for the optical filter on the silicon substrate due to extremely high flexibility, robustness and extremely high function expansibility.
With the rapid development of emerging fields such as optical communication/optical interconnection systems, optical sensing/optical measurement, etc., a higher demand is being placed on the FSR of the filter. For example, for the 400g CWDM8 (Coarse Wavelength Division Multiplexer ) optical module of the next generation data center network, a new generation of 8-channel coarse wavelength division multiplexer with a channel interval of 20nm needs to be developed, and the working bandwidth is as high as 160nm, which is doubled compared with the CWDM4 optical module. However, the conventional multimode waveguide grating filter generally adopts phase apodization to realize high side mode rejection ratio, and the FSR is limited to 120nm due to the coupling of forward and reverse fundamental modes introduced by the symmetrical grating, which can not meet the performance requirements of next-generation optical communication and optical interconnection.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a filter based on a sub-wavelength multimode waveguide grating.
The technical scheme adopted by the invention is as follows:
the multimode sub-wavelength grating-based filter of the present invention includes a mode demultiplexer for multiplexing and demultiplexing of a fundamental mode and a high-order mode; the sub-wavelength grating comprises a mode field weak constraint regulation and control for a fundamental mode and a high-order mode; including a pass-through waveguide for the output of the fundamental mode.
The mode demultiplexer, the sub-wavelength grating and the through waveguide are connected in sequence.
The sub-wavelength grating comprises a front gradual change sub-wavelength grating, a multimode sub-wavelength grating and a rear gradual change sub-wavelength grating which are sequentially connected, wherein the input end of the front gradual change sub-wavelength grating is connected with the output end of the mode demultiplexer, and the output end of the rear gradual change sub-wavelength grating is connected with the input end of the through waveguide.
The input end of the front gradual change sub-wavelength grating is used as the input end of the sub-wavelength grating, and the output end of the rear gradual change sub-wavelength grating is used as the output end of the sub-wavelength grating.
The multimode sub-wavelength grating is a sub-wavelength grating structure, and particularly is a tooth-shaped structure formed by a fine waveguide arranged along the central position of the input propagation direction of the filter and a series of rectangular structures distributed on two sides of the fine waveguide, wherein the series of rectangular structures are arranged in parallel at intervals and are perpendicular to the input propagation direction of the filter; the teeth and tooth grooves of each rectangular structure form a sub-wavelength grating unit, and every two adjacent sub-wavelength grating units form a Bragg grating unit.
The multimode sub-wavelength grating realizes grating apodization through the dislocation size distribution of two sub-wavelength grating units in each Bragg grating unit along the propagation direction perpendicular to the input of the filter according to the gradual change distribution of a change function.
The change function is a Gaussian function, a Hamming function, a sine function or the like.
The multimode sub-wavelength grating meets the phase matching condition (n0+nm)/2=lambda/lambda, and realizes reverse coupling of a fundamental mode into a high-order mode at the Bragg wavelength, wherein n0 is the effective refractive index of the fundamental mode, nm is the effective refractive index of the mth-order mode, lambda is the Bragg wavelength, and lambda is the grating tooth period.
The multimode sub-wavelength gratings may be distributed in a symmetrical or antisymmetric configuration.
The front gradient sub-wavelength grating and the rear gradient sub-wavelength grating are both sub-wavelength grating structures, and specifically are gradient tooth-shaped structures formed by gradient waveguides arranged along the central position of the input propagation direction of the filter and series rectangular structures distributed on two sides of the gradient waveguides, wherein the series rectangular structures are arranged in parallel at intervals and are perpendicular to the input propagation direction of the filter; the heights of the tail ends of the teeth of each rectangular structure along the two sides of the transmission direction of the input of the filter are consistent, the gradual change waveguides of the front gradual change sub-wavelength grating and the rear gradual change sub-wavelength grating are respectively distributed gradually according to a change function along the transmission direction and the transmission reverse direction of the input of the filter, the tooth groove low end depth of the teeth of each rectangular structure is changed from shallow to deep, and the low loss conversion of a common waveguide mode into a Buloch mode in the sub-wavelength grating waveguide is realized.
The change function is a linear function or a second-order function, etc.
The mode demultiplexer comprises an input single-mode waveguide, a downloading single-mode waveguide, a mode demultiplexing working area and a front connection gradual change waveguide, wherein the output end of the input single-mode waveguide and the input end of the downloading single-mode waveguide are respectively connected with one end of the mode demultiplexing working area, the input end of the input single-mode waveguide and the output end of the downloading single-mode waveguide are free ends, the other end of the mode demultiplexing working area is connected with the input end of the front connection gradual change waveguide, and the output end of the front connection gradual change waveguide is connected with the input end of the front gradual change sub-wavelength grating of the sub-wavelength grating.
The input end of the input single-mode waveguide is used as the input port of the mode demultiplexer and is also the input port of the multimode sub-wavelength grating filter; the output end of the front connection gradual change waveguide is used as the output port of the mode demultiplexer; the output end of the downloading single-mode waveguide is used as a downloading port of the mode demultiplexer and is also a downloading port of a signal reflected by the multimode sub-wavelength grating filter; the output end of the through waveguide is the through port of the multimode sub-wavelength grating filter.
The through waveguide comprises a rear connection gradual change waveguide and a through single-mode waveguide which are sequentially connected, and the input end of the rear connection gradual change waveguide is connected with the output end of the rear gradual change sub-wavelength grating of the sub-wavelength grating.
The input end of the rear connection gradual change waveguide is used as the input end of the through waveguide, and the output end of the through single-mode waveguide is used as the output port of the through waveguide, and is also the through port of the multimode sub-wavelength grating filter.
The mode demultiplexer is specifically an adiabatic graded coupling waveguide, an asymmetric directional coupling waveguide or a grating auxiliary coupling waveguide and the like.
The filter of the multimode sub-wavelength grating is applied to a cascade multichannel filter and a tunable filter.
The beneficial effects of the invention are as follows:
1. the invention realizes more flexible bandwidth adjustment range compared with the traditional multimode waveguide grating filter by introducing the structure of the sub-wavelength grating and the regulation and control on the weak constraint of the mode field, can realize filters with different bandwidth requirements, and can realize flattened and low-loss spectral response.
2. The invention obviously reduces the change of the local refractive index of the grating in apodization by utilizing an excellent dispersion regulation mechanism of a sub-wavelength grating structure and a corresponding apodization mode, realizes a grating filter with high side mode rejection ratio, can realize a filter without FSR limitation, and meets the requirements of the next generation of high-capacity multi-channel wavelength division multiplexing transmission.
3. The invention introduces the reflected signal of the high-order mode and the mode multiplexer, has the advantages of large tolerance and small loss, and realizes the add-drop multiplexing of the wavelength signals.
4. The invention can be manufactured by planar integrated optical waveguide technology, only needs one etching, has simple technology, low cost and small loss, is compatible with the traditional CMOS technology, and has the potential of large-scale production.
In summary, the on-chip waveguide type add-drop filter with high flexible bandwidth adjustment range, high side mode rejection ratio, low loss and flat-top spectrum is obtained by introducing multimode sub-wavelength grating and apodization technology, and the on-chip waveguide type add-drop filter has the advantages of simple process, excellent performance and the like.
Drawings
FIG. 1 is a schematic diagram of the overall structure of a multimode sub-wavelength grating filter;
FIG. 2 is a schematic diagram of the operating principle of a multimode sub-wavelength grating filter;
FIG. 3 is a schematic diagram of an apodized grating of a multimode sub-wavelength grating filter;
FIG. 4 is a graph of simulation results of a multimode sub-wavelength grating of a grating filter of an example device;
in the figure: 1. a mode demultiplexer 2, a sub-wavelength grating 3, a through waveguide 01, an input single-mode waveguide 02, a downloading single-mode waveguide 03, a mode demultiplexing working area 04, a front gradual change waveguide 05, a front gradual change sub-wavelength grating 06, a multimode sub-wavelength grating 07, a rear gradual change sub-wavelength grating 08, a rear connection gradual change waveguide 09 and a through single-mode waveguide.
Detailed Description
The invention will be described in further detail with reference to the accompanying drawings and specific examples.
As shown in fig. 1, the multimode sub-wavelength grating based filter of the present invention comprises a mode demultiplexer 1 for multiplexing and demultiplexing of a fundamental mode and a higher order mode, a sub-wavelength grating 2 for mode field weak confinement modulation of the fundamental mode and the higher order mode, and a pass-through waveguide 3 for output of the fundamental mode. The mode demultiplexer 1, the sub-wavelength grating 2 and the through waveguide 3 are connected in sequence. The mode demultiplexer 1 is specifically an adiabatic graded coupling waveguide, an asymmetric directional coupling waveguide, a grating auxiliary coupling waveguide, or the like.
The sub-wavelength grating 2 comprises a front gradual change sub-wavelength grating 05, a multimode sub-wavelength grating 06 and a rear gradual change sub-wavelength grating 07 which are sequentially connected, wherein the input end of the front gradual change sub-wavelength grating 05 is connected with the output end of the mode demultiplexer 1, and the output end of the rear gradual change sub-wavelength grating 07 is connected with the input end of the through waveguide 3. The input end of the front graded sub-wavelength grating 05 is used as the input end of the sub-wavelength grating 2, and the output end of the rear graded sub-wavelength grating 07 is used as the output end of the sub-wavelength grating 2.
The multimode sub-wavelength grating 06 is a sub-wavelength grating structure, in particular a tooth-shaped structure formed by a thin waveguide arranged along the central position of the input propagation direction of the filter and a series of rectangular structures distributed on two sides of the thin waveguide, wherein the series of rectangular structures are arranged in parallel at intervals and are perpendicular to the input propagation direction of the filter; the teeth and tooth grooves of each rectangular structure form a sub-wavelength grating unit, and every two adjacent sub-wavelength grating units form a Bragg grating unit, as shown in fig. 3.
The multimode sub-wavelength grating 06 realizes grating apodization through the dislocation size distribution of two sub-wavelength grating units in each Bragg grating unit along the propagation direction perpendicular to the input of the filter according to the gradual change distribution of the change function; the change function is a gaussian function, a hamming function, a sine function, or the like.
The multimode sub-wavelength grating 06 satisfies the phase matching condition (n0+nm)/2=λ/Λ, and realizes reverse coupling of the fundamental mode into a higher-order mode at the bragg wavelength, where n0 is the effective refractive index of the fundamental mode, nm is the effective refractive index of the mth-order mode, λ is the bragg wavelength, and Λ is the grating tooth period. The multimode sub-wavelength grating 06 may be distributed in a symmetrical or anti-symmetrical configuration.
The front gradient sub-wavelength grating 05 and the rear gradient sub-wavelength grating 07 are sub-wavelength grating structures, in particular to a gradient tooth-shaped structure formed by gradient waveguides arranged along the central position of the input propagation direction of the filter and series rectangular structures distributed on two sides of the gradient waveguides, wherein the series rectangular structures are arranged in parallel at intervals and are perpendicular to the input propagation direction of the filter; the heights of the tail ends of the teeth of each rectangular structure along the two sides of the transmission direction of the input of the filter are consistent, the gradual change waveguides of the front gradual change sub-wavelength grating 05 and the rear gradual change sub-wavelength grating 07 are respectively gradually distributed along the transmission direction and the transmission reverse direction of the input of the filter according to a change function, the depth of the tooth socket low end of each tooth of each rectangular structure is changed from shallow to deep, and the low loss conversion of a common waveguide mode into a Bloch mode in the sub-wavelength grating waveguide is realized; the change function is a linear function or a second order function, etc.
The mode demultiplexer 1 comprises an input single-mode waveguide 01, a download single-mode waveguide 02, a mode demultiplexing working area 03 and a front connection gradual change waveguide 04, wherein an output end of the input single-mode waveguide 01 and an input end of the download single-mode waveguide 02 are respectively connected with one end of the mode demultiplexing working area 03, the input end of the input single-mode waveguide 01 and the output end of the download single-mode waveguide 02 are free ends, the other end of the mode demultiplexing working area 03 is connected with the input end of the front connection gradual change waveguide 04, and the output end of the front connection gradual change waveguide 04 is connected with the input end of the front gradual change sub-wavelength grating 05 of the sub-wavelength grating 2. The input end of the input single-mode waveguide 01 is used as the input port of the mode demultiplexer 1 and is also the input port of the multimode sub-wavelength grating filter; the output end of the front connection gradual change waveguide 04 is used as the output port of the mode demultiplexer 1; the output end of the downloading single-mode waveguide 02 is used as a downloading port of the mode demultiplexer 1 and is also a downloading port of a signal reflected by the multimode sub-wavelength grating filter; the output end of the through waveguide 3 is the through port of the multimode sub-wavelength grating filter.
The through waveguide 3 comprises a rear connection gradual change waveguide 08 and a through single-mode waveguide 09 which are sequentially connected, and the input end of the rear connection gradual change waveguide 08 is connected with the output end of the rear gradual change sub-wavelength grating 07 of the sub-wavelength grating 2. The input end of the rear connection gradual change waveguide 08 is used as the input end of the through waveguide 3, and the output end of the through single-mode waveguide 09 is used as the output port of the through waveguide 3 and is also the through port of the multimode sub-wavelength grating filter.
As shown in fig. 2, which is the working principle of the present invention, the mode demultiplexer 1, the sub-wavelength grating 2 and the through waveguide 3 are sequentially connected, wherein an upper left port is an input port, a lower left port is a download port, and a right port is a through port. Here, an example is given of a TE mode operating in the transverse electric mode, in which the sub-wavelength grating 2 reflects the TE1 mode. The TE0 mode input from the left end of the mode demultiplexer 1 can be output in TE0 mode from the right end without loss, and vice versa; while TE1 mode input from the right end may be coupled into TE0 mode and output from the lower left port in TE0 mode. The multimode sub-wavelength grating meets the phase matching condition of TE0 mode and reverse TE1 mode, is an antisymmetric grating, and the TE0 mode of the multimode sub-wavelength grating is input, and can be reversely coupled to form TE1 mode near the Bragg wavelength resonance condition, the reflected TE1 mode is output from the lower left port through the mode demultiplexer 1, and the unreflected TE0 mode is output from the through port, thereby realizing the add-drop multiplexing of wavelength signals. By optimizing the overall width of the sub-wavelength grating 2, the grating misalignment size and the grating period, filters with different center wavelengths and bandwidths can be obtained.
The multimode sub-wavelength grating realizes suppression of spectral sidebands by adopting an apodization technology, so that square spectral response with high side-mode suppression ratio is obtained. As shown in fig. 3, in the configuration of the apodized sub-wavelength grating, the offset (i.e., δ in the figure) of the two sub-wavelength gratings in the vertical propagation direction is adjusted in the bragg grating unit composed of the two sub-wavelength gratingsTo achieve apodization, delta is distributed gradually along the propagation direction, the variation trend is small-large-small, as shown in figure 3, a Gaussian function is used to define the variation trend of delta, namely delta=delta 0 exp[-b(z-L/2) 2 /L 2 ]Wherein delta 0 In order to obtain the grating dislocation value with the largest dislocation value in the middle of the grating, b is apodization intensity, z is the grating position along the propagation direction, and L is the length of the multimode sub-wavelength grating. The greater the apodization intensity b is selected, the higher the side mode rejection ratio can be obtained.
Specific embodiments of the invention are as follows:
silicon nanowire optical waveguides based on silicon-on-insulator SOI materials are selected: the core layer is made of silicon material, the thickness is 220nm, and the refractive index is 3.4744; the lower/upper cladding materials are SiO 2 Lower cladding SiO 2 Thickness of 2 μm, upper cladding SiO 2 The thickness was 1 μm and the refractive index was 1.4404.
For the mode demultiplexer 1 of the multimode sub-wavelength grating filter, a structure of adiabatic graded coupling waveguide is adopted.
For the anti-symmetric multimode sub-wavelength grating structure of the multimode sub-wavelength grating filter, the parameters are selected such that the total width of the multimode sub-wavelength grating is 1200nm, the maximum value of grating dislocation value of the sub-wavelength grating 2 is 90nm, the period of the sub-wavelength grating 2 is 206nm, the period number of the sub-wavelength grating 2 is 400, the duty ratio of the sub-wavelength grating 2 is 0.5, the period number of front/back gradual change sub-wavelength gratings 05 and 07 is 40, the width of the middle thin waveguide is 100nm, the apodization form is Gaussian apodization, and the apodization strength is 10.
As shown in FIG. 4, the simulation result of the simulation verification is that the center wavelength of the device is about 1550nm, the 1dB bandwidth is 20nm, the loss is less than 0.1dB, the side mode rejection ratio of the left side and the right side of the frequency spectrum is 25dB and 27dB respectively, the frequency spectrum has a flattened channel and higher steepness, the frequency spectrum has more ideal square spectral response, the free spectral range FSR of the frequency spectrum is more than 350nm, and the FSR of the traditional multimode waveguide grating of 120nm is broken. It can be seen that the device of the present invention can achieve an on-chip optical filter with low loss, high side-mode rejection ratio, and an ultra-large free spectral range.
The above-described embodiments are intended to illustrate the present invention, not to limit it, and any modifications and variations made thereto are within the spirit of the invention and the scope of the appended claims.
Claims (10)
1. A multimode sub-wavelength grating-based filter, characterized by:
a mode demultiplexer (1) comprising multiplexing and demultiplexing for a fundamental mode and a higher order mode;
the optical grating comprises a sub-wavelength grating (2) used for mode field weak constraint regulation of a fundamental mode and a high-order mode;
comprising a through waveguide (3) for the output of the fundamental mode.
2. The multimode sub-wavelength grating based filter of claim 1, wherein: the sub-wavelength grating (2) comprises a front gradual change sub-wavelength grating (05), a multimode sub-wavelength grating (06) and a rear gradual change sub-wavelength grating (07) which are sequentially connected, wherein the input end of the front gradual change sub-wavelength grating (05) is connected with the output end of the mode demultiplexer (1), and the output end of the rear gradual change sub-wavelength grating (07) is connected with the input end of the through waveguide (3).
3. The multimode sub-wavelength grating based filter of claim 2, wherein: the multimode sub-wavelength grating (06) is a sub-wavelength grating structure, in particular a tooth-shaped structure formed by a waveguide arranged along the central position of the input propagation direction of the filter and a series of rectangular structures distributed on two sides of the waveguide, wherein the series of rectangular structures are arranged in parallel at intervals and are perpendicular to the input propagation direction of the filter; the teeth and tooth grooves of each rectangular structure form a sub-wavelength grating unit, and every two adjacent sub-wavelength grating units form a Bragg grating unit.
4. A multimode sub-wavelength grating based filter according to claim 3, characterized in that: the multimode sub-wavelength grating (06) realizes grating apodization through the dislocation size distribution of two sub-wavelength grating units in each Bragg grating unit along the propagation direction perpendicular to the input of the filter according to the gradual change distribution of a change function;
the change function is a Gaussian function, a Hamming function or a sine function.
5. The multimode sub-wavelength grating based filter of claim 2, wherein: the multimode sub-wavelength grating (06) meets the phase matching condition (n0+nm)/2=lambda/lambda, and realizes reverse coupling of a fundamental mode into a high-order mode at the Bragg wavelength, wherein n0 is the effective refractive index of the fundamental mode, nm is the effective refractive index of the mth-order mode, lambda is the Bragg wavelength, and lambda is the grating tooth period.
6. The multimode sub-wavelength grating based filter of claim 2, wherein: the front gradual change sub-wavelength grating (05) and the rear gradual change sub-wavelength grating (07) are all sub-wavelength grating structures, and specifically are gradual change tooth-shaped structures formed by gradual change waveguides arranged along the central position of the input propagation direction of the filter and series rectangular structures distributed on two sides of the gradual change waveguides, wherein the series rectangular structures are arranged in parallel at intervals and are perpendicular to the input propagation direction of the filter; the heights of the tail ends of the teeth of each rectangular structure at two sides of the transmission direction of the input of the filter are consistent, and the graded waveguides of the front graded sub-wavelength grating (05) and the rear graded sub-wavelength grating (07) are graded and distributed according to a change function along the transmission direction and the transmission reverse direction of the input of the filter respectively, so that the conversion of a common waveguide mode into a Buloch mode in the sub-wavelength grating waveguide is realized;
the change function is a linear function or a second-order function.
7. The multimode sub-wavelength grating based filter of claim 2, wherein: the mode demultiplexer (1) comprises an input single-mode waveguide (01), a download single-mode waveguide (02), a mode demultiplexing working area (03) and a front connection gradual change waveguide (04), wherein the output end of the input single-mode waveguide (01) and the input end of the download single-mode waveguide (02) are respectively connected with one end of the mode demultiplexing working area (03), the input end of the input single-mode waveguide (01) and the output end of the download single-mode waveguide (02) are free ends, the other end of the mode demultiplexing working area (03) is connected with the input end of the front connection gradual change waveguide (04), and the output end of the front connection gradual change waveguide (04) is connected with the input end of the front gradual change sub-wavelength grating (05) of the sub-wavelength grating (2).
8. The multimode sub-wavelength grating based filter of claim 2, wherein: the through waveguide (3) comprises a rear connection gradual change waveguide (08) and a through single-mode waveguide (09) which are sequentially connected, and the input end of the rear connection gradual change waveguide (08) is connected with the output end of the rear gradual change sub-wavelength grating (07) of the sub-wavelength grating (2).
9. The multimode sub-wavelength grating based filter of claim 1, wherein: the mode demultiplexer (1) is specifically an adiabatic graded coupling waveguide, an asymmetric directional coupling waveguide or a grating auxiliary coupling waveguide.
10. Use of a multimode sub-wavelength grating based filter according to any one of claims 1-9, characterized in that: the filter of the multimode sub-wavelength grating is applied to a cascade multichannel filter and a tunable filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311405720.1A CN117471608A (en) | 2023-10-27 | 2023-10-27 | Filter based on multimode sub-wavelength grating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311405720.1A CN117471608A (en) | 2023-10-27 | 2023-10-27 | Filter based on multimode sub-wavelength grating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117471608A true CN117471608A (en) | 2024-01-30 |
Family
ID=89634070
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311405720.1A Pending CN117471608A (en) | 2023-10-27 | 2023-10-27 | Filter based on multimode sub-wavelength grating |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117471608A (en) |
-
2023
- 2023-10-27 CN CN202311405720.1A patent/CN117471608A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4361030B2 (en) | Mode splitter and optical circuit | |
| Okamoto | Wavelength-division-multiplexing devices in thin SOI: Advances and prospects | |
| CN109870767B (en) | Grating type single-fiber three-way multiplexer | |
| CN111736266B (en) | PON-oriented WDM1r wave combiner | |
| CN108445586B (en) | Band-pass filter irrelevant to polarization based on silicon-based waveguide grating | |
| CN109407209B (en) | Optical wavelength division-mode division hybrid multiplexing demultiplexer based on mode converter and Bragg waveguide grating | |
| JP5625449B2 (en) | Mach-Zehnder interferometer, arrayed waveguide diffraction grating, and method of manufacturing Mach-Zehnder interferometer | |
| CN213661636U (en) | Wavelength division multiplexer/demultiplexer, photonic integrated chip and optical module | |
| CN101915961A (en) | Multi-cascade fiber bragg grating filter | |
| US20060222296A1 (en) | Optical wavelength division multiplexer | |
| CN111226147B (en) | Echelle grating multiplexer or demultiplexer | |
| CN110568555B (en) | Sub-wavelength multi-mode Y-branch waveguide | |
| Rabus | Realization of optical filters using ring resonators with integrated semiconductor optical amplifiers in GaInAsP/InP | |
| GB2488308A (en) | Optical Filter | |
| CN100565257C (en) | Reconstructing light top and bottom path multiplexer based on 2 D photon crystal | |
| Huang et al. | Arrayed waveguide grating DWDM interleaver | |
| CN115236799B (en) | Grating type lithium niobate optical filter with transverse amplitude apodization | |
| CN112558227B (en) | Double-layer MZI filter insensitive to temperature and preparation | |
| CN117471608A (en) | Filter based on multimode sub-wavelength grating | |
| CN116088096A (en) | Dual-input dual-output mode converter and design method | |
| CN112327518B (en) | Novel array waveguide grating based on lithium niobate thin film | |
| CN114755759A (en) | Ultra-compact arrayed waveguide grating wavelength division multiplexer based on sub-wavelength grating | |
| CN112462535A (en) | Silicon-based electro-optical modulation and mode division multiplexing integrated device | |
| Xia et al. | On the design of microring resonator devices for switching applications in flexible-grid networks | |
| US6842253B2 (en) | Constructing method for an optical passive component |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |